How to Build a WhatsApp AI Customer Service Bot with n8n (No Code, Free & Open Source)

Most WhatsApp bot tutorials show you a toy "hello world" chatbot. This guide builds a production-ready AI customer service bot that actually handles real customer conversations — with CRM integration, conversation memory, and human handoff. Stack: n8n (free, open-source) + WhatsApp Cloud API (free) + OpenAI GPT-4o Time to build: ~2 hours | Monthly cost: ~$5-15 (just OpenAI API calls) Architecture Overview Customer → WhatsApp → Meta Cloud API → Webhook → n8n ↓ AI Agent (GPT-4o) ↓ ┌─── Knowledge Base ├─── CRM (Supabase/Airtable) └─── Human Handoff (Slack/Email) ↓ n8n → WhatsApp API → Customer Step 1: Set Up WhatsApp Cloud API (Free) Go to developers.facebook.com → Create App → Business type Add WhatsApp product Get your Phone Number ID and Access Token from the WhatsApp > API Setup page Set up a webhook URL (we'll create this in n8n next) Important: Generate a permanent token via System Users in Business Settings. The temporary token expires in 24 hours. Step 2: Create the n8n Webhook In